EVALUATION OF SOME CHEMICALS IN PROTECTING APPLE SEEDLINGS FROM SOME PATHOGENIC SOIL FUNGI

AL - Windawi, D.S.J.; S. Juber, K.

	EVALUATION OF SOME CHEMICALS IN PROTECTING APPLE SEEDLINGS FROM SOME PATHOGENIC SOIL FUNGI
The Iraqi Journal of Agricultural Science
Article 1, Volume 38, Issue 2, 2007, Pages 41-51
Authors
D.S.J. AL - Windawi; K. S. Juber
Abstract
This experiment was conducted to isolate and identify fungi that associated with apple roots, testing the pathogenicity of the high frequency isolated fungi and evaluating the efficiency of chemical compounds in protecting the seedlings from the infection by some pathogenic soil fungi. Results showed that 16 genera of fungi were associated with diseased plants, with variable percentages of occurrence. Rhizoctonia solani had the highest percentages of occurrence ,followed by Fusarium solani, Cylindrocarpon coprsomae and C. obtusisporum , Alternaria alternatia , Fusarium graminearum, F.eguseti .Verticillum dahliae , Macrophomiua phaseollna and Phoma betae were found in one or two samples and in low frequency. Preliminary pathogenicity test for sixteen isolates of Cylln drocarpon coprsotnae , C. obtusisporum, Fusarium eguseti, F. graminearum , F. so/ani, Macrophomina phaseollna, P/101Il1l betae , Rhizoctonla solani and Verttcillum dahliae by using cabbage seeds showed the superiority of Risolani isolate (Rh.1) in inhibiting seed germination (zero), followed by Risolanl (Rh.2) (1'10), M. Pliaseollna (Mp.1), and Pibetae (Pb.1) isolates (3% gcrrnlnatlou) then c. Coprsonutc (Cy.1) isolate S% germlnation, whereas they ranged 10%-36% for the other fungi. Pathogenicity test on apple seedlings for six fungal species, C. Coprsomae (Cy.l ), Esotant (Fs.2), Risolanl (Rid), Pibetae (Pb.1), Vutottttac (VeI.I), and M. Pttaseolina (Mp.1) revealed that disease severity ranged between 56.0% ¬78.5% ill manifested seedling with fungi compared with the control treatment (no infestation) which had zero disease severity. Treatments with bion, salicylic acid and the fungicide bchanol significantly decrease in severity of pathogenic fungi isolates and significant increased dr)' weight of root and shoot as compared with the check. Resuhs indicated that treatment with behanol of 1.0 mIll significantly decreased disease severity to 15.3%-19.3%. However treatment with salicylic acid 1.0 mM reduced disease severity between 39.3%-55.0% while treatment of bion at 75 mg/l reduced disease severity to 33.3%-50.0% as compared with treatment of pathogenic fungi 58.3%-91.0%.

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